The hip abductor muscles are responsible for lifting your thigh out to the side. They also stabilize your pelvis when you walk or stand on one leg. The primary hip abductors are the gluteus minimus and medius and the tensor fasciae latae. The sartorius and the piriformis are secondary hip abductors.
Gluteus Minimus and Medius
The gluteus minimus arises from the outer surface of the pelvis, known as the ilium. It attaches to the greater trochanter, a prominent knob of bone on the outer thigh bone, or femur. The gluteus minimus is covered by the much larger gluteus medius, which originates along the upper rim, or crest, of the ilium and inserts onto the greater trochanter. When they contract, they pull the side of the pelvis and the outside of the thigh toward each other, abducting the hip.
Tensor Fasciae Latae
Running along the outside of the thigh from the crest of the ilium to the shin bone is a sheet of tough connective tissue called the iliotibial band, or fascia latae. The tensor fasciae latae is a muscle that attaches at the front of the crest of the ilium and inserts into the iliotibial band. When it contracts, it tightens the iliotibial band and abducts the hip. The large buttock muscle, the gluteus maximus, also attaches to the iliotibial band and can help abduct the hip.
The sartorius is the longest muscle in your body. It runs diagonally from the point of bone at the front of the ilium across the front of the thigh to the inner shin bone just below the knee. The sartorius is a secondary abductor of the thigh. Its primary job is to fold the legs into a cross-legged position. It takes its name from the Latin sartor, or tailor, referring to the cross-legged seat tailors used to favor while working.
The piriformis is primarily an external rotator of the hip, but it also assists with hip abduction. It originates on the front surface of the sacrum, the triangular-shaped bone that forms the back of the pelvis, and inserts onto the greater trochanter of the femur. Several other muscles that lie close to the piriformis similarly externally rotate the hip and can assist with abduction, including the obturator internus and the gemellus superior and inferior.